Optic neuritis is a common optic nerve disorder usually affecting individuals between the ages of 15 and 45. The pathogenesis is related to demyelination regardless of whether or not multiple sclerosis is present. Because there were no established guidelines to follow in deciding upon a treatment for a patient with this condition, the Optic Neuritis Treatment Trial (ONTT) was initiated. The ONTT protocol was designed to determine the value of corticosteroids in the treatment of optic neuritis. Two primary outcome measures, contrast sensitivity and visual field sensitivity, and two secondary outcome measures, color discrimination and visual acuity, were utilized to assess treatment efficacy. The major objective of this research project is to conduct a detailed analysis of visual field data from the ONTT. Although visual field information was used as an outcome measure in the ONTT study, only general summary values were examined. This project will incorporate a thorough evaluation of visual field data from the ONTT that is directed to four primary issues: (1) Determine the relationship of specific patterns of visual field loss to final visual outcome, recurrences of visual loss and treatment. (2) Quantitatively characterize the loss and recovery of visual field sensitivity in optic neuritis. (3) Evaluate the interrelationships among patient response characteristics, test conditions and visual field results. (4) Compare existing visual field analysis procedures and develop new methods of quantitatively evaluating and characterizing visual field loss. The visual field database for the ONTT provides a unique opportunity to evaluate visual field loss in optic neuritis. The use of stringent test protocols, the standardization of equipment and test procedures, the training and certification of visual field technicians, the quality control assessment of all visual field examinations, the high compliance of patients in meeting their scheduled appointments, and the automated data conversion and processing procedures all ensure that the ONTT visual field database is of higher quality than any previous multi-center study. These factors, in conjunction with the size of the patient population, the large number of. visual field examinations per patient, and the high compliance for scheduled followup visits make it possible to conduct a detailed examination of visual field properties in optic neuritis, determine the prognostic value of specific visual field characteristics, and evaluate the possibility of additional differences in visual field properties among treatment groups. In addition, the variety of visual field deficits that are present in optic neuritis makes the ONTT database an ideal resource for developing and evaluating different quantitative visual field analysis procedures.